Using a converter, I see that the bar spacing is .4 inches which would be ideal for all finches except possibly the tiny Goldbreasts. And the interior width is approximately 35 inches. So this would allow room to fly, to a degree, if you keep perches spaced well apart..
So in my opinion it would be ok for finches. But height doesn't really affect the number of birds it will keep, as they will all want to be on the highest perch anyway, to claim their territory. In other words, this size cage, in spite of it's height, would still really only be suitable for one to 2 pairs of finches. It is the length and width that determine how many can usually get along in a cage.
While they may well be very glad to have the extra space to move around and explore, it will still not allow for any more birds than if you had the same cage size, but only half as tall.
I'd say go for it if you only want a pair or two. Because it is tall, they will be less stressed out when you approach the cage, than if you had a smaller cage, sitting lower down. They would feel safer as they would be perching up near your eye level. Put feeders near the bottom and they will make use of all the space, and it will minimize the mess from scattered food.